An email alerting agents to the postponement of Woodstock 50's ticket on-sale has prompted fears that the 100,000-person anniversary concert will be canceled, although founder Michael Lang cast the fears as merely "rumors" late Friday.

"Woodstock is a phenomenon that for fifty years has drawn attention to its principles and also the rumors that can be attached to that attention," Lang, one of the co-founders of the original 1969 event in Bethel Woods, New York, said in a statement to Billboard, adding that fears of its demise were "just more rumors."

Earlier today, talent manager Amanda Phelan with Woodstock 50 talent-buyer Danny Wimmer Presents sent an email to agents representing acts at the concert in Watkins Glen, New York, explaining, "There is currently a hold on the Woodstock 50 on-sale date. We are waiting on an official press statement from Woodstock 50 regarding updated announce, ticket pricing, and overall festival information. We will get this information to you as soon as we receive it."

Tickets for the three-day event with headliners The Killers, Dead and Co, Imagine Dragons and Jay-Z and were supposed to go on sale Monday (April 22) in honor of Earth Day. No new date has been announced and the delay has prompted concern from managers and agents with acts playing the multi-genre festival.

“There’s always been lots of rumors around Woodstock," said Lang on March 5 when responding to questions about why he was planning to wait more than a month after putting tickets on sale to announce the lineup.

"We have excellent partners and an incredible talent lineup of over 80 artists which will be announced within the next couple of weeks. We’re preparing a once in a lifetime event,” he said.

Billboard has spoken with representatives for a number of acts on the lineup who say most artists have already been paid the deposits for their performances.

"No one knows what the hell is going on but there is clearly a problem," one agent with an act playing the Aug. 16-18 event says, adding that the fact the Lang and the Woodstock 50 team can't get the event on sale likely means an issue with investors or site complications at the Watkins Glen International Speedway, which is scheduled to host this year's event.